Proponents of new dams call rivers that empty into the ocean "wasted" water. They believe that new dams create water. And they are wrong.
Our existing reservoirs are seldom filled. This is an arid place. Building more dams can't change that. At a very high cost, more dams would allow us to catch more water in only the wettest years.
New dams fuel growth with the illusion of more available water. Then the next multi-year drought comes and the new dam is just another empty reservoir, surrounded by the new, thirsty neighborhoods it spawned.
We all want more water than this climate has. We take nearly all of the above-ground water and borrow from the water "bank" under our feet. But just as getting another credit card makes our financial problems worse, building more dams just lets us keep spending more water than we have and makes our water debt problems grow.
As long as the water table keeps dropping and historically year-round rivers run dry, we are overdrawn at the water bank. At great cost, new dams on already heavily dammed rivers fuel demand more than they provide supply. Therefore, they are not part of the solution.